Field of Invention
The invention relates to a fan and, in particular, to an impeller of a fan.
Related Art
With the raised requirement of the heat dissipation for systems, more and more fans with different sizes are utilized. A fan on the operation can induce an airflow to take away the heat generated by an object. For a general fan structure, a plurality of blades are disposed on the periphery of the hub of the fan and can rotate to cause an airflow. However, if the center of gravity of the fan is shifted from the fan's center, the fan's vibration or shaking will occur.
The above-mentioned vibration or shaking not only causes the fan to generate noises but also makes the fan shaft fatigue more easily and rapidly, and therefore the lifespan of the fan will be reduced or the heat dissipation efficiency will deteriorate so that the product quality of the fan is reduced. The current solution for this problem is to dispose a plurality of balance rooms in the impeller of the fan. FIG. 1 is a schematic diagram showing some balance rooms of the impeller of a conventional fan. As shown in FIG. 1, the conventional impeller 1 includes a plurality of recesses 11 disposed at the top portion 12 of the impeller 1. Some objects are disposed in the recesses 11 for functioning as balance elements 13, such as weights, and thus the impeller can be balanced on the fan's operation in the manner of adding weight. However, when the fan is operated, the added balance elements 13 may fly out and leave the recesses 11 due to the inertia force. Therefore, the fan will lose the balance effect, and thus the overmuch vibration caused by the fan's operation will further deteriorate the fan's quality. Besides, in the prior art, an additional mold is required for the balance elements 13 for assuring the balance element 13 and the recess 11 of a tight fit therebetween to avoid the separation of the balance element 13 from the recess 11 on the fan's operation. Besides, the exposed recesses 11 also affect the fans' characteristic and the dust will be accumulated in the recesses.